KR101610983B1 - Production of grafted polyethylene from renewable materials, the obtained polyethylene and uses thereof - Google Patents

Abstract

The present invention relates to a process for the preparation of grafted polyethylene comprising the steps of: a) fermenting a renewable starting material and optionally refining to produce at least one alcohol selected from a mixture of alcohols comprising ethanol and ethanol step; b) dehydrating the obtained alcohol to produce at least one alkene selected from a mixture of ethylene and an ethylene containing alkene in a first reactor, optionally refining said alkene to obtain ethylene; c) polymerizing ethylene in a second reactor to obtain polyethylene; d) isolating the polyethylene obtained in step c); e) an unsaturated carboxylic acid or a functional derivative thereof, an unsaturated dicarboxylic acid having 4 to 10 carbon atoms and a functional derivative thereof, a C ₁ -C ₈ alkyl ester of an unsaturated carboxylic acid or a glycidyl ester of an unsaturated carboxylic acid Grafting the polyethylene with at least one graft monomer selected from a metal salt of a carboxylic acid, a derivative thereof, or a metal salt of an unsaturated carboxylic acid. The present invention also relates to grafted polyethylene obtained by said process, copolymers and compositions comprising said polyethylene, and uses of said polyethylene.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of grafted polyethylene from renewable materials, to the obtained polyethylenes and to their use. BACKGROUND OF THE INVENTION < RTI ID = 0.0 >

The present invention relates to a process for preparing grafted polyethylene from renewable starting materials.

In particular, it relates to a process for preparing grafted polyethylene from ethylene obtained by dehydration of an alcohol resulting from fermentation of a renewable starting material; Preferably, the renewable starting material is a plant material.

The earliest polyolefin made for industrial use is polyethylene. Several types of polyethylene exist and are generally classified according to their density.

High density polymers (HDPE, high density polyethylene) generally have a density of 0.940 to 0.965 g / cm3; Such polyethylene is distinguished by a low degree of branching and consequently strong intermolecular forces or high tensile strength. Low branching is provided by the choice of catalyst and reaction conditions.

Medium density polymers (MDPE, medium density polyethylene) generally have a density of 0.925 to 0.940 g / cm3; Such polyethylene exhibits good impact properties.

The low density polymer (LDPE, low density polyethylene) generally has a density of 0.915 to 0.935 g / cm < 3 >; Such polymers exhibit a high degree of branching of the chains (short or long chains). These polyethylene exhibit low tensile strength and increased ductility.

Linear low density polymers (LLDPE, linear low density polyethylene) generally have a density of 0.915 to 0.935 g / cm3; Such polymers are present in a substantially linear form with a plurality of short branches.

The ultra low density polymer (VLDPE, ultra low density polyethylene) generally has a density of 0.860 to 0.910 g / cm < 3 >; Such polymers are present in substantial linear form with a very large number of short branches.

In addition, there is a sub-category depending on the molecular weight of the polyethylene or the polyethylene.

In addition, polyethylene is often used in combination with a second material other than polyethylene. For example, it is possible to produce a multilayer film comprising one or more layers of polyethylene and one or more other layers of a second material. As examples of the second material, polar polymers and also metals, metal alloys or oxides thereof can be mentioned. As the polar polymer, mention may be made of nitrogen-containing and / or oxygen-containing polymers, for example, saponified copolymers or polyesters of polyamide, ethylene and vinyl acetate. However, these materials do not adhere to or adhere weakly to polyethylene. Therefore, in order to bond the two layers of the polyethylene layer and the second layer in the multilayer film, it is necessary to use the polyethylene layer and the intermediate layer "tie " attached to the second layer. Although polyethylene of renewable origin is described in the prior art, for example in document US 2007/0219521, there is no tie prepared from a renewable starting material which is able to combine the present polyethylene layer with the second material layer.

Advantageously and surprisingly, the inventors of the present patent application used an industrial manufacturing method of a specific polyethylene, which is grafted polyethylene used for producing ties, from renewable starting materials.

The process according to the invention makes it possible to prepare at least a portion of the starting materials of fossil origin and to replace the starting materials of fossil origin with renewable starting materials.

In addition, the polyethylene obtained according to the process according to the invention is of such a quality as can be used in any article known to use grafted polyethylene, including the most difficult articles.

In particular, it is possible to produce ties from renewable starting materials which are capable of bonding a polyethylene layer with a polar polymer and also with a second material selected from metals, metal alloys or oxides thereof.

The gist of the present invention is a process for producing grafted polyethylene comprising the steps of:

a) fermenting the renewable starting material and optionally refining to produce at least one alcohol selected from a mixture of alcohols comprising ethanol and ethanol;

b) dehydrating the obtained alcohol to produce at least one alkene selected from a mixture of alkenes comprising ethylene and ethylene in a first reactor and optionally purifying said alkene to obtain ethylene;

c) polymerizing ethylene in a second reactor to obtain polyethylene;

d) isolating the resulting polyethylene according to the result of step c);

e) reacting said polyethylene with an unsaturated carboxylic acid or a functional derivative thereof, an unsaturated dicarboxylic acid having from 4 to 10 carbon atoms and a functional derivative thereof, a C ₁ -C ₈ alkyl ester of an unsaturated carboxylic acid or an unsaturated carboxylic acid Grafting with at least one graft monomer selected from glycidyl ester derivatives, or metal salts of unsaturated carboxylic acids.

Another point of the invention is that the polyethylene, or more generally at least some of the carbon atoms, obtainable by the process according to the invention is a renewable source and that part of said renewable source is in accordance with standard ASTM D 6866-06 Which is grafted by the graft monomer capable of being determined.

A further aspect of the present invention is a copolymer and a composition comprising polyethylene, and also the use of said polyethylene.

Other features, aspects or features of the present invention will become apparent from the following description.

Step a) of the process for the production of polyethylene according to the invention comprises the fermentation of a renewable starting material for the preparation of one or more alcohols, said alcohols being selected from mixtures of alcohols comprising ethanol and ethanol.

The renewable starting materials are natural resources, such as animal or vegetable, and their storage capacity can be reformed over a short period of time on a human scale. In particular, it needs to be updated as quickly as the storage amount is consumed. For example, vegetable materials represent an advantage that they can be grown without consuming conspicuously reducing natural resources.

Unlike materials produced from fossil materials, the renewable starting material contains ^14C . All carbon samples collected from a living organism (animal or plant) is a mixture of the fact that the three isotopes: ¹² C (refers to about 98.892%), ¹³ C (about 1.108%) and ¹⁴ C (very small amount: 1.2 × 10 ^{- 10} %). The ¹⁴ C / ¹² C ratio of living tissue is the same as that of the atmosphere. In the environment, ¹⁴ C exists in two main forms: organic forms, such as the form of carbon dioxide gas (CO ₂ ) and the form of carbon incorporated into organic molecules.

In living organisms, since carbon is constantly exchanged with the external environment, the ¹⁴ C / ¹² C ratio is kept constant by metabolism. Since the ratio of ¹⁴ C in the atmosphere is constant, the amount of ¹⁴ C in living organisms is the same, because the organisms absorb the ¹⁴ C as much as they absorb the ambient ¹² C. The average ¹⁴ C / ¹² C ratio is 1.2 × 10 ^{- 12} .

¹² C is stable, ie the number of ¹² C atoms in the provided sample is constant over time. ¹⁴ C is radioactive; The number of ¹⁴ C atoms in the sample decreases with time (t), and its half-life is 5730 years.

^{The 14} C content is substantially constant from the extract of the renewable starting material until the end of the life of the preparation of the polyethylene according to the invention and the object made of said polyethylene.

As a result, the presence of ¹⁴ C in the material is an indication of whether its amount is related to the origin of the molecules making up the material, that is, whether it is a renewable starting material or not.

The amount of ¹⁴ C in the material can be measured by one of the methods described in standard ASTM D 6866-06 (Standard Test Methods for Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis).

This standard includes three methods of measuring organic carbon produced from renewable starting materials, referred to as "bio-based carbon ". The proportion of the polyethylene represented by the present invention is preferably determined by mass spectrometry or liquid scintillation analysis as described in the standard, and more preferably by mass spectrometry.

By this measurement method to measure the ¹⁴ C / ¹² C isotope ratio in the sample, compared with ¹⁴ C / ¹² C isotope ratio in the biogenic material to provide a 100% basis, of the organic carbon in the sample The percentage is measured.

Preferably, the polyethylene according to the invention comprises more than 20% by weight, preferably more than 50% by weight, based on the total carbon weight of the polyethylene, of carbon produced from the renewable starting material.

That is, the polyethylene may contain at least 0.24 x 10 ^-10 wt% of ¹⁴ C, preferably 0.6 x 10 ^-10 wt% or more of ¹⁴ C.

Advantageously, the amount of carbon produced from the renewable starting material is greater than 75 wt%, preferably 100 wt%, based on the total carbon weight in the polyethylene.

As a renewable starting material, a plant or animal origin material may be used which is produced from a plant material, an animal-derived material, or a recovered material (recycled material).

In the present invention, the plant origin material includes at least sugar and / or starch.

Vegetable materials including sugars are essentially sugarcane and sugar beet; Also, maple, date palm, candy palm, sorghum or American agave can be mentioned; Vegetable materials comprising starch are essentially cereals and legumes such as corn, wheat, barley, sorghum, rice, potato, cassava or sweet potato, or algae.

Of the substances resulting from the recovered material, mention may be made in particular of vegetable or organic waste containing sugars and / or starches.

Preferably, the renewable starting material is a plant material.

Fermentation of the renewable material takes place in the presence of one or more suitable microorganisms; Such microorganisms may be naturally modified by, or optionally genetically modified by, chemical or physical stresses; The term used here is a mutation. Typically, the microorganism used is Saccharomyces cerevisiae cerevisiae ) or mutants thereof.

As the renewable starting material, cellulose or hemicellulose, or lignin, which can be converted into a sugar-containing substance in the presence of a suitable microorganism can be used. Such renewable materials advantageously include straw, wood or paper that can originate from the recovered material.

It is not limited to the list shown above.

Preferably, the fermentation step is followed by a purification step to separate ethanol from other alcohols.

The alcohol (s) obtained to produce one or more alkenes selected from a mixture of ethylene and ethylene-containing alkenes in the first reactor are dehydrated in step b) and the by-product by dehydration is water.

(잔여 Na₂O (대략 0.04 %) 를 많이 포함하지 않는 비도핑된 3엽 (trilobe) 알루미나) 으로 판매되는 촉매를 사용하여 수행된다.Generally, the dehydration is carried out using alumina, preferably a gamma-alumina based catalyst, such as ESM 110

(Non-doped trilobe alumina that does not contain much of the residual Na ₂ O (approximately 0.04%)).

Working conditions for dehydration are part of the general knowledge of those skilled in the art; As a proof, dehydration is generally carried out at a temperature of about 400 ° C.

Another advantage of the process according to the invention is energy saving: the fermentation and dehydration steps of the process according to the invention are carried out at a relatively low temperature of less than 500 ° C, preferably less than 400 ° C; In contrast, the cracking and steam cracking steps for obtaining ethylene are carried out at a temperature of about 800 < 0 > C.

Energy saving is also CO ₂ emitted into the atmosphere ≪ / RTI >

Preferably, the purification step is carried out during step a) or b).

Purification of the alcohol (s) obtained in any of the purification steps (a), purification of the alkene (s) obtained in step b) is advantageously carried out in the presence of an adsorbent for conventional filters such as molecular sieves, zeolites, Lt; / RTI >

If the alcohol obtained in step a) is purified enough to isolate ethanol, the alkene obtained in step b) is ethylene.

If the alcohol obtained in step a) is not purified, a mixture of alkenes comprising ethylene is obtained according to the results of step b).

Advantageously, one or more purification steps are carried out during step a) and / or b) to obtain ethylene having a purity sufficient to effect polymerization. It is preferred to obtain ethylene which preferably has a purity of more than 85% by weight, preferably more than 95% by weight, preferably more than 99% by weight, more preferably more than 99.9% by weight. Particularly preferably, the alcohol obtained in step a) is purified to such an extent that ethanol is isolated; As a result, the alkene obtained in step b) is ethylene.

The major impurities present in ethylene resulting from the dehydration of ethanol are ethanol, propane and acetaldehyde.

Advantageously, the ethylene should be purified, i.e. ethanol, propane and acetaldehyde must be removed in order to be able to polymerize easily in step c).

Ethylene, ethanol, propane and acetaldehyde can be separated by performing at least one cryogenic distillation.

The boiling point of the compound is as follows:

Ethylene, ethanol, propane and acetaldehyde are cooled to approximately -105 ° C, preferably -103.7 ° C, and then ethylene is distilled off.

Another advantage of the process according to the invention relates to impurities. The impurities present in ethylene resulting from the dehydration of ethanol are completely different from those present in ethylene resulting from cracking or steam cracking. In particular, impurities present in ethylene produced from cracking or steam cracking include dihydrogen and methane, in which case whatever the composition of the initial feedstock is, it does not matter.

Typically, the dihydrogen and methane are compressed to 36 bar and cooled to about -120 DEG C and then separated. Under these conditions, the liquid dihydrogen and methane are separated from the demethanizer and then ethylene is recovered at 19 bar and -33 ° C.

The process according to the present patent application makes it possible to omit the step of separating the two hydrogens and methane, and it is also possible to cool the mixture from atmospheric pressure to -105 ° C instead of -120 ° C at 36 bar. The cooling of the separation step can also take place under pressure to increase the boiling point of the separated compound (for example at about 20 bar and -35 캜). This difference also contributes to making the process according to the invention more economical (equipment savings and energy savings achieved by reducing the level of CO ₂ released into the atmosphere).

Another advantage is that, in contrast to the ethylene obtained by cracking or steam cracking, the ethylene obtained in step b) of the process according to the invention does not contain acetylene. In fact, acetylene is highly reactive and causes oligomerization side reactions; It is therefore particularly advantageous to obtain ethylene free of acetylene.

Another advantage is that the process according to the invention can be carried out in a production unit located at the production site of the starting material. In addition, the size of the production unit of the process according to the invention is much smaller than the size of the purification device: in particular, the purification device is a large device which is generally located remotely from the production center of the starting material and fed via a pipeline.

The polymerization step c) of ethylene can be carried out in different ways depending on the type of polyethylene to be synthesized.

Preferably, the polyethylene to be synthesized is LLDPE.

LLDPE can be synthesized according to two main methods: solution method and fluidized bed (gaseous) method.

The solution process may be carried out by introducing ethylene into the autoclave reactor or tubular reactor in the presence of one or more solvents and one or more comonomers. The reactor can be adiabatically activated or an external cooler can be installed.

The comonomer used is an alpha-olefin having 3 to 10 carbon atoms and more particularly selected from olefins having 4, 6 or 8 carbon atoms; Particularly preferably, the -olefin is selected from hex-1-ene, 2-methylpentene and oct-1-ene.

The catalyst used can be of the Ziegler-Natta or metallocene type, or less of the Phillips type.

Ziegler-Natta catalysts typically consist of halogen derivatives of Group IV and V transition metals (titanium, vanadium) and alkyl compounds of Group I to Group III metals in the Periodic Table of the Elements.

The metallocene catalyst is a single-site catalyst consisting essentially of one atom which is a metal which may be zirconium or titanium and two cycloalkyl molecules bonded to said metal; More specifically, the metallocene catalyst is usually composed of two cyclopentadiene rings bonded to the metal. Such catalysts are frequently used with aluminoxane, preferably methylaluminoxane (MAO), as a cocatalyst or activator. Hafnium can also be used as the metal to which the cyclopentadiene is attached. Other metallocenes may include Group IVa, Va, and VIa transition metals. Lanthanide metals may also be used.

Phillips catalysts are obtained by laminating chromium oxide on a support (silica or silica aluminum) having a high specific surface area of about 400 to 600 m < 2 > / g. These catalysts are then reduced and activated at high temperatures (400-800 ° C).

The temperature of the reactor is generally from 150 to 300 DEG C and the pressure is from 3 to 20 MPa.

At the reactor outlet, the gas enriched in the monomer is returned to the inlet of the reactor, and the liquid stream containing the polyethylene is processed to separate the polyethylene from the solvent. The polyethylene is then conveyed to an extruder.

According to the fluidized bed or gas phase process, the reaction medium is composed of catalytic particles formed around polyethylene, ethylene and comonomers. The polyethylene produced while ethylene and the comonomer form the carrier gas of the fluidized bed remains solid. Also, the injection of ethylene and comonomer can remove heat in the reaction and control the polymerization temperature.

The comonomers used are? -Olefins of 3 to 10 carbon atoms, more especially those selected from olefins of 4 to 8 carbon atoms; Particularly preferably, the -olefin is selected from but-1-ene and hex-1-ene, or 2-methylpentene.

The catalyst used can be of the Ziegler-Natta, Metallocene or Phillips type.

The temperature of the reactor is generally from 80 to 105 DEG C and the pressure is from 0.7 to 2 MPa.

This reaction is carried out in a vertical reactor. The ethylene is compressed to the required pressure and introduced into the inlet (bottom portion) of the reactor. The reaction pressure can be controlled by controlling the pressure of ethylene at the inlet of the reactor. The catalyst and optional cocatalyst, and comonomer (s) are introduced into the reactor along with ethylene.

At the reactor outlet, the gas mixture and polyethylene are extracted from the fluidized bed, and then the pressure is reduced to separate the polyethylene from the gas. The constituents of the gas mixture (ethylene and comonomer) are separated and optionally returned to the reactor. The polyethylene (solid) is purged to remove as much ethylene as possible and transferred to the extruder.

Low density (radical) polyethylene is produced by radical polymerization of ethylene at high pressure.

Two reactors are used for LDPE synthesis: an autoclave reactor and a tubular reactor.

The reaction medium consists of a polymer and a monomer solution; The resulting polymer is isolated by continuous reduction under pressure, is converted into granules after being taken up by the extruder in a molten state.

High density polyethylene (HDPE) can be synthesized by two main methods, suspension polymerization method and gas phase method.

The two methods can be carried out using a Phillips type catalyst or a Ziegler type catalyst, or a metallocene type catalyst.

Thus, in a suspension polymerization process in which a Phillips catalyst is used, the reaction is carried out in a suspension in a liquid hydrocarbon, generally isobutene; See particle-type processes. The medium temperature is about 100 캜, and the pressure should be such that the medium is maintained in the liquid, i.e., about 3 MPa.

A suspension polymerization method in which a Ziegler catalyst is used is carried out using an organometallic compound, for example a titanium trichloride based catalyst in combination with an alkylaluminum chloride; The reaction is carried out in suspension in hexane-type hydrocarbons. The medium temperature is slightly below 100 ° C and the pressure is a few megapascals.

Generally, comonomers such as but-1-ene and hex-1-ene are used to control the density of polyethylene, and hydrogen is used to control the molecular weight.

The use of a metallocene catalyst makes it possible to produce particularly preferred polyethylene, "metallocene polyethylene" or "m-PE ".

In the case of linear low density polymers, they are polyethylene with a very narrow molecular weight distribution and a uniformly distributed short branch; This is referred to as "m-LLDPE ".

Preferably, the polyethylene produced in step c) of the process according to the present patent application is "m-LLDPE ", which is a metallocene linear low density polyethylene prepared according to a fluidized bed process using a metallocene catalyst.

The polyethylene obtained in step c) is subsequently isolated (step d). The polyethylene is then passed directly to the extruder or other reactor to which the grafting treatment is to be applied.

The isolated polyethylene according to the result of step d) is then grafted.

As subsequently described, the grafting of the polyethylene can be carried out using unsaturated carboxylic acids or functional derivatives thereof, unsaturated dicarboxylic acids having from 4 to 10 carbon atoms and functional derivatives thereof, C ₁ -C ₈ alkyl esters of unsaturated carboxylic acids or A glycidyl ester derivative of an unsaturated carboxylic acid, or a metal salt of an unsaturated carboxylic acid.

The polymer is grafted using an unsaturated carboxylic acid. The use of functional derivatives of such acids does not depart from the scope of the present invention.

Examples of the unsaturated carboxylic acid include those having 2 to 20 carbon atoms such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid. Functional derivatives of such acids include, for example, anhydrides, ester derivatives, amide derivatives, imide derivatives and metal salts of unsaturated carboxylic acids (for example, alkali metal salts).

Unsaturated dicarboxylic acids having 4 to 10 carbon atoms and functional derivatives thereof, especially their anhydrides, are particularly preferred graft monomers.

Such graft monomers include, for example, maleic acid, fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, cyclohex-4-ene-1,2-dicarboxylic acid, 4-methylcyclohex- Dicarboxylic acid, bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid or x-methylbicyclo [2.2.1] hept- Dicarboxylic acid, or 4-methylcyclohex-4-ene-dicarboxylic acid anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride, allylsuccinic anhydride, cyclohex- 1,2-dicarboxylic acid anhydride, bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic anhydride and x-methylbicyclo [2.2.1] hept- , 2-dicarboxylic acid anhydride.

Examples of other graft monomers include C ₁ -C ₈ alkyl esters of unsaturated carboxylic acids or glycidyl ester derivatives of unsaturated carboxylic acids, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl Acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethyl maleate, monomethyl fumarate, dimethyl fumarate, monomethyl itaconate, and diethyl itaconate Nate; Amide derivatives of unsaturated carboxylic acids such as acrylamide, methacrylamide, maleimino amide, maleimide, maleic N-monoethylamide, maleic N, N-diethylamide, maleic N-monobutylamide, N-dibutylamide, fumaronoamide, fumaridamide, fumaric acid N-monoethylamide, fumaric acid N, N-diethylamide, fumaric acid N-monobutylamide and fumaric acid N, N-dibutylamide; Imide derivatives of unsaturated carboxylic acids such as maleimide, N-butyl maleimide and N-phenyl maleimide; And metal salts of unsaturated carboxylic acids such as sodium acrylate, sodium methacrylate, potassium acrylate and potassium methacrylate. Glycidyl methacrylate is preferred. More preferred is maleic anhydride.

According to a particular alternative form, maleic anhydride comprising a carbon atom of renewable origin may be used.

The maleic anhydride can be obtained according to the method described in the applicant's FR 0854896 application and the international application PCT / FR2009 / 051426 of the cited applicants, and one of the alternative manufacturing forms comprises the following steps:

a) fermenting and optionally purifying the renewable starting material to produce a mixture comprising at least butanol;

b) oxidizing butanol to obtain maleic anhydride at a temperature of typically 300 to 600 ° C, using an oxide-based catalyst of vanadium and / or molybdenum;

c) isolating the maleic anhydride obtained from the result of step b).

The preparation of maleic anhydride containing carbon atoms of renewable origin is described in detail on page 2 line 21 to page 8, line 15 of the international application PCT / FR2009 / 051426, which is incorporated herein by reference.

One advantage of using maleic anhydride generated from renewable resources is that the amount of non-renewable resources for making the polymer is more limited.

In addition, one advantage of the present method is that the fermentation further limits the number of isomers of butanol than the chemical route of hydroformylation of propylene. Butanol obtained by fermentation of the renewable starting material is particularly suitable. In particular, the butanol produced from the fermentation of the renewable starting material exhibits a lower isobutanol / n-butanol ratio than the purified butanol produced from the fossil starting material, in this case before any isolation step of n-butanol. Isobutanol and n-butanol exhibit very similar physicochemical properties and are therefore expensive to separate these products. Thus, it is believed that the provision of n-butanol deficient in isobutanol is a major economic advantage to the process which is the subject of the present invention, since it is possible to produce maleic anhydride of good quality at low cost.

Various methods known in the art for grafting graft monomers to polyethylene may be used. Such formulations may contain additives generally used during the polyolefin process, such as 10 ppm to 5% of additives, such as antioxidants, such as substituted phenolic molecular antioxidants, UV protectants, processing agents such as fatty amides, stearic acid, (Known as inhibitors of extrusion defects), amine-based defogging agents, antiblocking agents such as silica or talc, dyed masterbatches, nucleating agents, and the like.

This may be accomplished by heating the polymer at a high temperature of from about 100 [deg.] C to about 300 [deg.] C, with or without the presence of a solvent, with or without a solvent.

Suitable solvents or mixtures thereof that can be used in the above reaction are benzene, toluene, xylene, chlorobenzene, cumene, and the like. Liquid and / or supercritical carbon dioxide is also considered a solvent or cosolvent in the type of process.

상품명으로 판매된다. 퍼옥시에스테르의 예로서, t-부틸 퍼옥시-2-에틸헥사노에이트 (Luperox 26), t-부틸 퍼옥시아세테이트 (Luperox 7), t-아밀 퍼옥시아세테이트 (Luperox 555), t-부틸 퍼벤조에이트 (Luperox P), t-아밀 퍼벤조에이트 (Luperox TAP) 및 OO-t-부틸 O-(2-에틸헥실) 모노퍼옥시카르보네이트 (Luperox TBEC) 가 언급될 수 있다. 디알킬 퍼옥시드로서, 2,5-디메틸-2,5-디(t-부틸퍼옥시)헥산 (Luperox 101), 디쿠밀 퍼옥시드 (Luperox DC), α,α'-비스(t-부틸퍼옥시)디이소프로필벤젠 (Luperox F40), 디(t-부틸)퍼옥시드 (Luperox DI), 디(t-아밀) 퍼옥시드 (Luperox DTA) 및 2,5-디메틸-2,5-디(t-부틸퍼옥시)헥스-3-인 (Luperox 130) 이 언급될 수 있다. 히드로퍼옥시드의 예는 t-부틸 히드로퍼옥시드 (Luperox TBH70) 이다. 예를 들어, 퍼옥시케탈로서, 1,1-디(t-부틸퍼옥시)-3,3,5-트리메틸시클로헥산 (Luperox 231), 에틸 3,3-디(t-부틸퍼옥시)부티레이트 (Luperox 233) 또는 에틸 3,3-디(t-아밀퍼옥시)부티레이트 (Luperox 533) 가 사용될 수 있다.Suitable radical generators that may be used include peroxides, preferably peroxyesters, dialkyl peroxides, hydroperoxides or peroxyketals. These peroxides are commercially available from Arkema ' s Luperox

It is sold as a product name. Examples of peroxy esters include t-butyl peroxy-2-ethylhexanoate (Luperox 26), t-butyl peroxyacetate (Luperox 7), t-amyl peroxyacetate (Luperox 555) Luperox P, t-amylperbenzoate (Luperox TAP) and OO-t-butyl O- (2-ethylhexyl) monoperoxycarbonate (Luperox TBEC) can be mentioned. As the dialkyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (Luperox 101), dicumyl peroxide (Luperox DC), α, (Luperox F40), di (t-butyl) peroxide, di (t-amyl) peroxide (Luperox DTA) and 2,5-dimethyl- -Butylperoxy) hex-3-yne (Luperox 130) can be mentioned. An example of hydroperoxide is t-butyl hydroperoxide (Luperox TBH70). For example, peroxyketals include 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane (Luperox 231), ethyl 3,3-di (t- butylperoxy) (Luperox 233) or ethyl 3,3-di (t-amylperoxy) butyrate (Luperox 533) may be used.

The graft reaction may be performed according to a batch solution process or a continuous process using a melt compounding apparatus.

In the case of a batch solution graft process, the polyethylene dissolved in the above-mentioned suitable solvent is brought to a reaction temperature in the presence of monomers and a radical generator, the reaction temperature and time being selected to match the decomposition kinetic energy of the radical generator, The generator can be introduced continuously. Preferably a temperature in the range of 50 to 200 DEG C is used. It is preferred to use a peroxyester group as the radical generator for the solution graft. The treatment of the grafted polyethylene is carried out by precipitation from non-solvent for the solution graft.

The term "non-solvent" is understood to mean an organic or inorganic solvent, or a mixture of organic or inorganic solvents, which is capable of dissolving more than 10% of the grafted polymer. By way of example, water, ketones, alcohols, esters and mixtures thereof may be mentioned. Following precipitation, grafted polyethylene is obtained in the form of a powder or aggregate by filtration and drying. The grafted polyethylene may optionally undergo further "washing" steps by solid / liquid extraction between itself and the above-mentioned non-wovens.

In the case of a continuous graft process, a device for extruding molten plastic known to a person skilled in the art is used. As an example, an internal mixer, an open mill, a uniaxial or counter-rotating or idle twin-screw extruder, or a continuous bore kneader may be mentioned. The grafting device may be one of the above-described devices or combinations thereof, such as a ball kneader equipped with a take-up shank, an idle twin-screw extruder equipped with a gear pump, and the like. In the case of an extruder, the device is arranged to identify the melting zone of the polymer, the blending and reaction zone between the existing entities, and the decompression / venting zone for removing the volatile compounds. The material configuration may be provided by such arrangement of the axes of the device, use of the confinement section or combination of devices in these different zones. The device may also be equipped with a filtration system and / or a strand or an underwater granulation system.

Polyethylene is introduced into the apparatus and the temperature of the body is selected to suit the decomposition kinetic energy of the radical generator. As the radical generator for the continuous graft, it is preferable to use a dialkyl peroxide, hydroperoxide or peroxyketal group. It is preferable to use a temperature in the range of 100 to 300 占 폚, more preferably 180 to 250 占 폚.

The polyethylene, graft monomers and radical generators can be introduced into the extruder simultaneously or separately. In particular, the monomers and radical generators may be introduced together with the polymer as a main source, either separately or separately, by liquid injection depending on the apparatus.

In the injection step, the monomers and / or radical generators may be combined with some of the solvents as mentioned above. Some of these solvents are intended to facilitate compounding between reactive entities and also removal of volatile compounds during the venting step.

In the depressurization / venting step, a liquefaction of volatile compounds and a vacuum suitable for polyethylene are applied, which can range in vacuum from several millibars to several hundreds.

Finally, the grafted polyethylene is recovered in granular form at the exit of the extruder using a granulating device.

In the polymer modified by the graft obtained in the above-mentioned manner, the amount of graft monomer may be selected in a suitable manner, but is preferably 0.01% to 10%, more preferably 600 ppm to 50,000 ppm.

According to one aspect of the invention, the graft is carried out on non-grafted polyethylene according to the invention, and on a combination of other polymers referred to as "coarse graft polymers ". The formulation is introduced into an extrusion apparatus together with a graft monomer and a radical generator. The ball graft polymer is different from the polyethylene according to the present invention, i.e. it does not have the same characteristics.

In particular, the ball graft polymer may be polyethylene having a density and / or ¹⁴ C different from that of the polyethylene according to the present invention.

However, any type of polymer may be used as the co-graft polymer. Examples of ball graft polymers include elastomers, homopolymers, and copolymers of the polyamide, polyester, polyvinyl, polyurethane or polystyrene types such as styrene-based copolymers such as SBR (styrene / butadiene rubber), styrene Styrene block copolymer (SBS), styrene / ethylene / butadiene / styrene block copolymer (SEBS) and styrene / isoprene / styrene block copolymer (SIS) can be mentioned. (Ethylene / propylene rubber, also referred to as EPM) and EPDM (ethylene / propylene / diene), ethylene (ethylene / / Carboxylic acid vinyl ester copolymers such as ethylene / vinyl acetate copolymers, ethylene / unsaturated (meth) acrylic acid ester copolymers or ethylene / unsaturated (meth) acrylic acid copolymers. Preferably, the co-grafted polymer is a polystyrene type or a polyolefin type.

The amount of grafted monomer is determined by analyzing the succinic functionality by FTIR spectroscopy. The MFI or melt flow index of the grafted polymer is preferably from 0.1 to 15 g / 10 min (ASTM D 1238, 190 DEG C, 2.16 kg), advantageously from 0.1 to 5 g / 10 min, preferably from 0.1 to 3 g / 10 min to be.

The present invention relates to a composition comprising non-grafted polyethylene obtained from a renewable source material and to a composition comprising grafted polyethylene obtained from a renewable source material.

This patent application is more particularly directed to ties containing the following, in particular several groups which can be used in coextrusion:

Grafted polyethylene according to the present invention optionally diluted in the additional polymer,

- a co-grafted combination of at least one co-graft polymer and non-grafted polyethylene according to step a) to d) according to the invention, optionally diluted in the additional polymer, said combination comprising an unsaturated carboxylic acid or a functional derivative thereof, To 10 carbon atoms and a functional derivative thereof, a C ₁ -C ₈ alkyl ester of an unsaturated carboxylic acid or a glycidyl ester derivative of an unsaturated carboxylic acid, or a metal salt of an unsaturated carboxylic acid 0.0 > and / or < / RTI >

As a result, the composition comprising polyethylene according to the present invention contains at least some of the polyethylene obtained from the regenerable material.

Additional polymers may be selected from ball graft polymers; And may be selected from grafted or non-grafted polyethylene according to the present invention.

Additional polymers comprising a combination of polymers are not outside the scope of the present invention.

The present invention relates to the use of grafted polyethylenes obtained from renewable raw materials, in particular coextrusion ties, impact modifiers in polymers (i.e. adjuvants in polymers which can increase the impact strength of the polymer) or compatibilizers for inorganic fillers (That is, an auxiliary agent capable of improving the possibility of mixing with an inorganic filler).

More particularly, the present invention is directed to the use of a coextrusion tie comprising polyethylene obtained from a renewable source material, its co-extrusion tie and the resulting multilayer structure comprising the structure.

Another embodiment of the tie according to the invention shows:

A first type of tie composition includes:

From 5 to 35% by weight of polyethylene having a density of from 0.860 to 0.960 grafted by at least one of the graft monomers described above;

5 to 95% by weight of non-grafted polyethylene;

from 0 to 60% by weight of at least one modifier selected from copolymers of ethylene with monomers selected from? -olefins, unsaturated carboxylic acid esters or saturated carboxylic acid vinyl esters, or polymers with elastomeric properties;

The grafted polyethylene is at least partially obtained from a renewable source material. Advantageously, the tie will not contain more than 5% by weight of the graft monomer.

The alpha -olefins that can be used as monomers are propylene, butene, hexene or octene.

Unsaturated carboxylic acid esters which can be used as monomers include alkyl (meth) acrylates whose alkyl has 1 to 24 carbon atoms, such as methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate or 2- Hexyl acrylate.

Saturated carboxylic acid vinyl esters which can be used as monomers are vinyl acetate or vinyl propionate.

The term "polymer with elastomeric properties" in accordance with the present patent application is understood to mean a polymer as defined in standard ASTM D412, i.e. a material that can be drawn at twice the length at ambient temperature is held for 5 minutes, After release, it can return to initial length within less than 10%. The term "polymer with elastomeric properties" is also understood to mean a polymer that can be drawn without having exactly the above characteristics and can be returned to its initial length.

By way of example, the following may be mentioned:

EPR (ethylene / propylene rubber, also representing EPM) and EPDM (ethylene / propylene / diene),

- styrene elastomers such as SBR (styrene / butadiene rubber), styrene / butadiene / styrene block copolymer (SBS), styrene / ethylene / butadiene / styrene block copolymer (SEBS) and styrene / isoprene / styrene block copolymer .

The first type of tie composition includes those described in patent application EP 1 136 536 A1 (except that the polyethylene used in the prior art patent application is not obtained from a renewable material).

More particularly, according to a first alternative form, the first type coextrusion tie comprises a composition (as described in EP 1 136 536 A1) comprising:

(A) itself consisting of a combination of 80 to 20 parts of a metallocene polyethylene (A1) having a density of 0.865 to 0.965, advantageously 0.865 to 0.94, and 20 to 80 parts of a nonmetallocene LLDPE polyethylene (A2) 35 parts (the combination of (A1) and (A2) is co-grafted with an unsaturated carboxylic acid as a graft monomer); And

- 95 to 65 parts of polyethylene (B) selected from polyethylene homopolymers or copolymers and elastomers; The combinations of (A) and (B) are as follows:

- the content of grafted unsaturated carboxylic acid is 30 to 10 ⁵ ppm;

- MFI or melt flow index (standard ASTM D 1238, 2.16 kg load at 190 占 폚) of 0.1 to 10 g / 10 min;

In the composition according to the present patent application, at least one of metallocene polyethylene (A1), nonmetallocene LLDPE polyethylene (A2) and polyethylene (B) is obtained at least partially from renewable raw materials.

According to a second alternative form, the first type of coextrusion tie comprises a composition (as described in EP 1 136 536 A1) comprising:

80 to 20 parts of a metallocene polyethylene (A1) having a density of 0.865 to 0.965, advantageously 0.865 to 0.94, and 20 to 80 parts of a nonmetallocene LLDPE polyethylene (A2) Wherein the combination of (A1) and (A2) is co-grafted by an unsaturated carboxylic acid;

- the content of grafted unsaturated carboxylic acid is 30 to 10 ⁵ ppm;

- MFI or melt flow index (standard ASTM D 1238, 2.16 kg load at 190 占 폚) of 0.1 to 10 g / 10 min;

Except that in the composition according to the present patent application, at least one of the metallocene polyethylene (A1) and the nonmetallocene LLDPE polyethylene (A2) is at least partially obtained from a renewable source material.

This patent application also discloses a layer comprising a coextrusion tie according to one of the above two alternative forms and a nitrogen-containing or oxygen-containing polar resin layer directly attached to the layer, such as a polyamide resin layer, A layer of a saponified copolymer (EVOH) of ethylene and vinyl acetate, or a polyester layer, or a metal layer (E).

Said layer (E) can also be at least partially obtained from a renewable source material.

Another aspect of the present invention is a rigid hollow body composed of a structure as described above.

A second type of tie composition includes:

A blend comprising 50 to 95% by weight of at least one polyethylene having a density of 0.860 to 0.960, advantageously 0.865 to 0.94, and 5 to 50% by weight of at least one polymer other than polyethylene, said blend comprising one of the grafted monomers described above By grafting);

Optionally, one or more non-grafted polyethylene having a density of 0.860 to 0.965,

Optionally one or more modifiers selected from copolymers of ethylene with monomers selected from alpha-olefins, esters of unsaturated carboxylic acids or vinyl esters of unsaturated carboxylic acids, or polymers with elastomeric properties,

Wherein the grafted polyethylene and / or non-grafted polyethylene is at least partially obtained from a renewable source material; Advantageously, the tie will not contain more than 5% by weight graft monomer.

The second type of tie composition includes those described in patent application EP 0 802 207 A1 (except that the prior art polyethylene used in this patent application is not obtained from a renewable material).

More particularly, according to this second alternative form, the second type of composition comprises a composition (as described in EP 0 802 207 A1) comprising:

At least one polyethylene or one ethylene copolymer chain (A),

At least one selected from (B) a polypropylene or propylene copolymer, (B2) a poly (1-butene) single- or copolymer and (B3) a polystyrene single- or copolymer,

(A) and (B) are grafted by a functional monomer and the grafted blend itself optionally comprises at least one polyolefin (C), or at least one polymer (D) having elastomeric properties, or (C) And (D);

The polyethylene or ethylene copolymer (A) is at least partially obtained from a renewable source material.

The polyethylene or ethylene copolymer (A) may be LDPE, HDPE, LLDPE, VLDPE or m-PE.

The patent application also discloses a layer comprising a coextruded tie of the second type described above, and a nitrogen-containing or oxygen-containing polar resin layer (E) directly attached to the layer, such as a polyamide resin layer, ethylene and vinyl acetate , A polyester resin layer, an inorganic oxide layer or a metal layer laminated on a polymer such as polyethylene, polyethylene terephthalate or EVOH.

The layer (E) may also be at least partially obtained from a renewable source material.

Another point of the present invention is a protective film composed of a co-extruded tie of the second type.

The third type of tie includes:

Polyethylene having a density of from 0.860 to 0.965, advantageously from 0.865 to 0.94, grafted by at least one of the graft monomers described above, and

Optionally, grafted polyethylene,

The grafted polyethylene and / or non-grafted polyethylene is at least partially obtained from a renewable raw material.

A third type of tie composition includes those described in patent application EP 1 400 566 A1 (except that the polyethylene used in the prior art patent application is not obtained from a renewable source material).

More particularly, said third type coextrusion tie comprises:

(A) itself 10 composed of a combination of 80 to 20% by weight of metallocene polyethylene (A1) having a density of 0.865 to 0.965, advantageously 0.865 to 0.94, and 20 to 80 parts of nonmetallocene LLDPE polyethylene (A2) Wherein the combination of (A1) and (A2) is co-grafted with a graft monomer selected from unsaturated carboxylic acids and derivatives thereof, wherein the content of graft monomers is 30 to 100,000 ppm;

40 to 60% by weight of a styrene / butadiene / styrene block copolymer (B) having 50 to 90 mol% of styrene;

- 20 to 35% by weight of polyethylene (C), the total sum being 100%; (A), (B) and (C) is such that the MFI or melt flow index (standard ASTM D 1238, 2.16 kg load at 190 占 폚) is between 0.1 and 10 g / 10 min;

At least one of metallocene polyethylene (A1), nonmetallocene LLDPE polyethylene (A2) and polyethylene (C) is at least partially obtained from a renewable source material.

The present patent application also relates to a multilayer structure comprising a third type coextrusion tie as described above and a layer (E) directly attached to one of the two sides of the layer (L), said layer (E) being a polystyrene Mono- or copolymer layer.

According to a preferred alternative embodiment, the multilayer structure comprises a layer (F) directly attached to a second side of a layer (L) located between layers (E) and (F) , An aliphatic polyketone, a saponified copolymer of ethylene and vinyl acetate (EVOH), a polymer layer selected from the group consisting of polyethylene, polyester and polystyrene, or a metal layer.

The layer (E) and / or (F) may also be at least partially obtained from a renewable source material.

Example

An example of the polymerization process is shown below. The following implementation is schematically illustrated in the accompanying drawings.

But was not carried out under any circumstances considered to be a constraint on the polymerization step of the process according to the invention.

A circuit for recirculating the gas comprising the two separators C ₁ and C ₂ of the cyclone type, the two heat exchangers E ₁ and E ₂ , the compressor C _p and the pump P, (R). ≪ / RTI >

The reactor R comprises a sub-zone which is a gas and liquid-receiving zone and a distribution plate (or distributor) D which limits the upper zone F in which the fluidized bed is located.

The dispenser (D) is a plate with a hole inserted therein; This distributor is intended to make the throughput of the gas entering the reactor uniform.

According to the present invention, a certain amount of ethylene and comonomer (1-hexene) was passed through the pipe (1) and then introduced into the reactor through which the polymerization was carried out in the fluidized bed via the pipe (2).

The fluidized bed comprises a catalyst and preformed polymer particles; The fluidized bed was maintained in a fluidized state by raising the gas stream originating from the distributor (D). The capacity of the fluidized bed was kept constant by withdrawing the polyethylene formed using the discharge pipe (11).

The polymerization of ethylene is an exothermic reaction; The temperature inside the reactor was kept constant by controlling the temperature of the gas being introduced (recycled) into the reactor through the pipe 10.

The unreacted molecules of ethylene and 1-hexene and the gas containing the transfer agent (hydrogen) are discharged from the reactor and enter the recycle circuit through the pipe 3. This gas can be treated in a cyclone type separator (C ₁ ) to remove possible fine particles of polyethylene that can be entrained. The treated gas is introduced into the first heat exchanger (E ₁ ) which is substantially cooled through the pipe (4). The gas exits the heat exchanger E ₁ through the pipe 5 and enters the compressor C _p , and the fluid exits through the pipe 6. The fluid is cooled in the second heat exchanger (E ₂ ) to such an extent that it condenses the comonomer. The pipe 7 transfers the fluid from the exchanger E ₂ to the cyclone type separator C ₂ . The gas is separated from the liquid in the separator (C ₂ ) of the cyclone type: the liquid is discharged from the separator (C ₂ ) of the cyclone via the pipe (10) and introduced into the reactor (R) C ₂ ), enters the pump (P), passes through the pipe (9), and then is introduced into the reactor through the pipe (2).

Polyethylene was prepared from ethylene which was carried out by carrying out steps a) and b) according to the method of the present application.

Three tests were performed on the apparatus using three fluids and the composition at the inlet of the reactor was as follows:

The reaction was carried out under the following working conditions:

Pressure of the reactor: 25 bar

Temperature of reactor: 90 ° C

Gas velocity: 0.6 m / s

Height of fluidized bed: 15 m

Fluid temperature at the inlet of the reactor: 40 ° C

Exit: 125 ㎏ / ㎥ / h.

The resulting polyethylene exhibits the following properties:

The flow index was measured according to standard ASTM D 1238 (190 占 폚; 2.16 kg). The density was measured according to standard ASTM D 1505.

The resulting polyethylene was then grafted by reactive extrusion: polyethylene was introduced into the extruder and the extrusion temperature was set at 200 占 폚. A mixture of maleic anhydride and dialkyl peroxide (50 wt.% / 50 wt.%) Was injected at one point in the extruder and the throughput (weight) was adjusted to 100 times greater than the peroxide / anhydride mixture. The grafted polymer was recovered at the extruder exit.

Claims (18)

A process for producing a grafted polyethylene, comprising the steps of:
a) fermenting the renewable starting material to produce at least one alcohol selected from a mixture of alcohols comprising ethanol and ethanol;
b) dehydrating the obtained alcohol to produce at least one alkene selected from a mixture of ethylene and an alkene comprising ethylene in a first reactor to obtain ethylene;
c) polymerizing ethylene in a second reactor to obtain polyethylene;
d) isolating the resulting polyethylene according to the result of step c);
e) an unsaturated carboxylic acid or a functional derivative thereof, an unsaturated dicarboxylic acid having 4 to 10 carbon atoms and a functional derivative thereof, a C ₁ -C ₈ alkyl ester of an unsaturated carboxylic acid or a glycidyl ester of an unsaturated carboxylic acid Grafting the polyethylene with at least one graft monomer selected from a metal salt of a carboxylic acid, a derivative thereof, or a metal salt of an unsaturated carboxylic acid. The method according to claim 1, wherein the renewable starting material is selected from cane and beet, maple, date palm, candy palm, millet, American agave, corn, wheat, barley, rice, potato, cassava, sweet potato or algae. ≪ / RTI > is a vegetable material. 3. The process according to claim 1 or 2, wherein the graft monomer is maleic anhydride. 3. The process according to claim 1 or 2, wherein the maleic anhydride is obtained from a renewable starting material. Process according to any one of the preceding claims, characterized in that the purification step during step a) or b) is carried out. Process according to any one of the preceding claims, characterized in that the polyethylene produced in step c) is "m-LLDPE ", a metallocene linear low density polyethylene prepared according to a solution process using a metallocene catalyst. Way. An unsaturated carboxylic acid or a functional derivative thereof, an unsaturated dicarboxylic acid having 4 to 10 carbon atoms and a functional derivative thereof, a C ₁ -C ₈ alkyl ester of an unsaturated carboxylic acid or a glycidyl ester derivative of an unsaturated carboxylic acid, Or a metal salt of an unsaturated carboxylic acid, wherein the polyethylene comprises carbon atoms derived from an animal or vegetable material. Comprising polyethylene according to claim 7, which can be obtained according to the process of claims 1 or 2, comprising an amount of carbon produced from regenerable starting material in excess of 20% by weight, based on the total carbon weight of the polyethylene, . A composition comprising polyethylene according to claim 7, which can be obtained according to the process of claims 1 or 2. A coextrusion tire comprising grafted polyethylene according to claim 7. 11. The coextrusion tie of claim 10, wherein the coextruded tie is diluted in the additional polymer. A coextruded tie comprising a co-grafted combination of polyethylene and at least one co-graft polymer obtained according to steps a) to d) of the process according to claim 1, characterized in that the combination comprises an unsaturated carboxylic acid or a functional derivative thereof, An unsaturated dicarboxylic acid having 4 to 10 carbon atoms and a functional derivative thereof, a C ₁ -C ₈ alkyl ester of an unsaturated carboxylic acid or a glycidyl ester derivative of an unsaturated carboxylic acid, or a metal salt of an unsaturated carboxylic acid Coextrusion tie that is co-grafted by one or more of the graft monomers. 13. The coextrusion tie of claim 12, wherein the coextruded tie is diluted in the additional polymer. A multi-layer structure comprising a coextrusion tie according to any one of claims 10 to 13. The polyethylene according to claim 7, which is prepared according to the process of claims 1 or 2 or as a compatibilizer for impact modifiers or inorganic fillers in polymers. Process according to claim 5, characterized in that the purification step is carried out after fermentation of the renewable starting material in step a). 6. Process according to claim 5, characterized in that the purification step is carried out after dehydration of the alcohol obtained in step b) to produce at least one alkene selected from a mixture of ethylene and ethylene-containing alkenes in the first reactor . 9. The polyethylene of claim 8, wherein the polyethylene comprises an amount of carbon produced from renewable starting material in an amount greater than 50% by weight based on the total carbon weight of the polyethylene.

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